[M4IF Technotes] iods & 3GPP

[AVARO Olivier FTRD/DIH/REN]

Hi Emre,
> What I mean is what is exactly stated in the 3GPP TS 26.234 
> spec. => "The receiving terminal is not required to implement 
> any of the specific MPEG-4 system architectural elements". 

I am afraid this sentence is broken since the ISO File Format is an integral part of the MPEG-4 Systems Architecture. It should indeed states "The receiving terminal is not required to implement any of the specific MPEG-4 Systems OD Framework", or better, reference the appropriate sections if you want to define the spec. by what you shall not do instead of what you shall do (which is strange by the way).
> Hence, what is not defined in ISO Media file format is out of 
> the scope of the 3GP file. 
Right. This does not prevent the ISO Media file format to be part of the MPEG-4 Systems architecture ...
> Of course, this does not restrict you from putting those 
> elements in the file. It simply means that the receiving 
> terminal can ignore them and still be able to  playback the 
> presentation. Only then that file is called a "3GPP compliant" file.
Exactly. I would say more : if you care about interoperability, you SHOULD also always make it and compliant with the MPEG-4 File Format. There is no extra burden in doing so expect the duplication created by the divergence of the formats.
> I think the necessary reasoning for the usage of the ISO 
> media file as the base format and introducing a new file 
> format has been done quite well in the 3GPP SA4 Group 
> discussions, which I am sure that you are very well aware of. 

No, I am not aware of the technical reasons.
Maybe you can summarize them for us.
Kind regards,
Olivier